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  • MSRP: n/a
  • Discontinued


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77 DX Documentation


Ribbon Microphone

The RCA 77 DX is a unique multipattern passive ribbon microphone, developed by RCA in the 1950’s. It was a successor to the 77D model, which itself followed several other 77 types.

The microphone employs an acoustic labyrinth, with a mechanical shutter behind the ribbon. A rotary control on the back of the mic’s grille rotates a metal shutter, which affects the behavior of the labyrinth. The effective result is a modification of the ribbon’s native figure-8 polar pattern.

The control had three marked options, U for Unidirectional (Cardioid), N for Nondirectional (Omni), and B for Bidirectional (Figure-8). The N and U patterns were highly frequency sensitive; off-axis sounds captured by the mic are colored by this variation in frequency response.

A second rotary control implemented a two-way high pass filter. The M for Music setting produced the flattest low-frequency response. The V1 and V2 Voice settings could be used to attenuate the mic’s response below 250Hz.

The RCA 77 DX is also known as: 77.


Pickup Patterns Pads & Filters
Ribbon Construction Impedance SPL/Noise
n/a n/a
Weight Length Max Diameter Interface(s)
n/a n/a n/a
    Power Specifications

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